textproduct: Quad Cities

KEY MESSAGES

- Another round of storms tonight, with the chance for some of them to be strong to severe.

- Turning cooler and breezy Tuesday behind a cold front, with dry conditions expected to then last through at least Thursday.

SHORT TERM /THROUGH TONIGHT/

Issued at 315 AM CDT Mon May 18 2026

Will walk out ongoing linear MCS that has become mainly outflow dominant, although a few isolated strong wind gusts may still occur. Also some isolated precursor WAA cells have developed ahead of the main line and with an elevated nature may produce some hail. Such a weakening larger system and inherent pressure perturbations may produce more trouble with wake low winds gushing out of the system's backside, possibly of 45 to 55+ MPH. Some of the CAMs even suggested this by mid morning south of I-80 acrs west central IL and far southeast IA. Areas of post-convective line stratiform rain with embedded thunder to be the last to clear as the morning progresses. Then again it's the same scenario of how much the convective debris can clear to allow for some heating, and also aided by breezy south to southwest sfc winds again this afternoon. Will go with 50 percentile widespread low 80s for highs today with sfc DPTs remaining in the 60s. The local area should remain dry while the current system lights up renewed convection to the south acrs central MO into central IL.

Tonight...may be a similar scenario as to what has and is occurring this Sunday night/Monday morning. The main upper trof will dig out acrs the east central plains with mid and upper jet support, and the main sfc front located along the MO RVR Valley. MCS generation tools all come together to suggest rapid and strong convection to fire late this afternoon from central KS and up the MO RVR Valley. Storm propagation vectors and CAPE "hunger" has this activity growing upscale and feeding east with aid of 40-50 KT SSW LLJ flow as another squall line moves east acrs IA and northern MO. There may be more support and a probable earlier start to allow some of this activity to still be strong to severe with damaging straight line winds(as opposed to this Monday AM) as the linear MCS arrives. 0-3KM shear vectors and LLVL THTA-E lapse rates may also support some meso- vortice type spin up tornadoes along any LEWP or comma head updraft- downdraft balance regions. Locally heavy rain with the passing storm lines with high rates, but again progressive nature of the system should preclude much of a widespread flash flood threat. Would expect a weakening trend with the convection as it propagates eastward acrs the rest of the DVN CWA into the late night hours and into early Tuesday morning as storm outflow outraces the main line again.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 315 AM CDT Mon May 18 2026

Tuesday...Morning convective debris and possibly a few post-frontal isolated light showers to eventually clear off for a blustery and cooler day. A large temp range acrs the CWA from west-to-east, with the east experiencing 12 hour high temps in the morning along and just post-frontal and then falling off into the 60s.

The rest of the week looks below normal under high pressure until moderation occurs into the start of the weekend. Also mainly dry until an upstream upper trof tries to battle it's way eastward into the ridge complex with some moisture draw for increasing precip chances by Friday.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 605 AM CDT Mon May 18 2026

Areas of showers and thunderstorms to continue to affect the TAF sites through mid to late morning with bouts of MVFR to IFR conditions. They may have an hour or two of higher wind gusts of 35-45 KTs, as well as swaths of wake low winds away from the storms with variable gusts of 40-50+ Kts. Thus sfc winds very uncertain and variable in both direction and speeds this morning until the convection diminishes by late morning and midday. Later today and afternoon gusty southerly winds will take over and mainly VFR clouds lingering into the evening. Then the watch will be on for another line of thunderstorms moving in from the west after 10 PM. This line will have the capability to produce strong straight line winds and passing bouts of heavy rainfall reducing VSBYs. Have tried to time out a 2 hour TEMPO window for the line based on a blend of the latest CAMs timing.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.